Field of the Invention
This invention relates to a damper device and a steering device which uses the damper device.
Description of Related Art
A steering device used for a vehicle changes the direction of steered wheels (tires) by reciprocally moving a rack shaft in an axial direction which is connected to the steered wheels through tie-rods. The rack shaft is slidably accommodated in a housing. The rack shaft is structured such that the reciprocal movement range of the rack shaft is physically restricted upon reaching to the limit of a reciprocal movement range by the collision of the large diameter portion formed at the end of the rack shaft with the housing. In more detail, accompanied by the operation of the steering wheel by a driver of the vehicle, the force which moves the rack shaft in an axial direction (forward force) is inputted. Vice versa, for example, when the steered wheel rides onto a curbstone, an excessive force is inputted from the steered wheel towards the rack shaft. Such excessive force moves the rack shaft in an axial direction (reverse force). Accompanied by the input of the forward or reverse force, when the rack shaft is moved in an axial direction until it collides with the housing, a so-called “end abutting” occurs.
In a steering device, a damper device is provided at the end abutting portion to absorb or dampen the impact generated upon end abutting operation. As a damper device, a device has been known which includes a rack shaft with a large diameter portion, a housing through which the rack shaft is movably inserted in an axial direction, the housing restricting the axial movement of the large diameter portion of the rack shaft, and an impact absorbing member which is inserted on a shaft portion of the rack shaft and is disposed between the end surface of the large diameter portion and the housing in an axial direction.
The steering device according to the Patent Literature 1 includes an elastic body (impact absorbing member) disposed between the end member (large diameter portion) and the housing. The impact absorbing member absorbs the collision impact while receiving the impact through the large diameter portion when the large diameter portion collides with the housing. The impact absorbing member includes an end plate (impact receiving member) which receives the collision impact upon contacting with the large diameter portion. The impact receiving member is formed with a restricting portion which contacts with a predetermined portion of the housing. In the Patent Literature 2, an impact absorbing member (damping member) is disclosed, which has an annular plate shaped restricting portion (stopper member) similar to that disclosed in the Patent Literature 1. The damper device according to the Patent Literature 3 includes an impact absorbing member (dampening member) provided at the end portion of the large diameter portion (rack end) facing to the housing. In detail, an annular shaped impact absorbing member is provided on and projecting from the end surface of the large diameter portion. A recessed portion which functions as a “restricting portion” of the Patent Literatures 1 and 2 is provided at the restricting surface of the housing. By the contact between the large diameter portion and the restricting surface of the housing, the compression displacement of the impact absorbing member in an axial direction can be restricted in a predetermined range.